Absorption spectra analysis of hydrated uranium(III) complex chlorides Original Research Article

Absorption spectra of powdered samples of hydrated uranium(III) complex chlorides of the formulas NH4UCl4 · 4H2O and CsUCl4 · 3H2O have been recorded at 4.2 K in the 4000–26 000 cm−1 range. The analysis of the spectra enabled the determination of crystal-field parameters and assignment of 83 and 77 crystal-field levels for the tetrahydrate and trihydrate, respectively. The energies of the levels were computed by applying a simplified angular overlap model as well as a semiempirical Hamiltonian representing the combined atomic and crystal-field interactions. Ab initio calculations have enabled the application of a simplified parameterization and the determination of the starting values of the AOM parameters. The received results have proved that the AOM approach can quite well predict both the structure of the ground multiplet and the positions of the crystal-field levels in the 17 000–25 000 cm−1 range, usually obscured by strong f–d bands.